Osteogenesis Imperfecta is the genetic disorder with which I was born. Luckily mine is a very mild case.
With the different structure of the cortex of the bone, x-rays often will not show hairline fractures when used at normal settings. This often leads to misdiagnosis of injuries for many mild OI patients and such mistakes may cause lifelong pain at the fracture site.
Many mild OI patients claim to 'know' when they are most vulnerable to breaks due to a perceived change in the blue sclera that is found in most patients. This claim has not been substantiated.
Mild OI patients can usually function normally in society with only moderate concern for their condition. For instance, I have had only 150 breaks in my life that I have counted (I stopped counting little things like fingers and toes a long time ago) and have learned many methods of avoiding fracture situations.
Even mild OI cases can demonstrate tendencies to stress fracture. One stress fracture that commonly occurs is in a metatarsal in the foot.
Stunted growth does occur in some of the mild cases, but not all cases. In fact, many mild OI patients grow to average proportions.
Genetic research, such as that done for Muscular Dystrophy, may eventually lead to a cure. Until then, OI remains a mysterious disease affecting less than 1% of America.